from brent jesse audiotubes website:
6922:
This is one of two premium versions of the 6DJ8 tube. First of all, it is the same tube as the 6DJ8, and will work wherever a 6DJ8 is needed. It has premium features such as low noise, low microphonics, and usually a longer lifespan....Most are factory screened for tight internal matching and low noise.
here is the whole page... if you really want to understand this topic thoroughly, especially regarding ALL the variants, read ALL of what is written here ...http://www.audiotubes.com/6dj8.htm
separately, these past detailed a-gon discussions may be helpful to those new to this party, or needing reminding of the knowledge base that many of us have benefitted from
https://forum.audiogon.com/discussions/tube-characterization-6dj8-6922-7308-cca-etc
https://forum.audiogon.com/discussions/tube-characterization-6dj8-6922-7308-part-ii